Written by Karla Hernandez (former SDSU Extension Forages Field Specialist).
Farm magazines are stressing the importance of reduced-lignin alfalfas and how they might benefit the farmer’s operation. However, more details are needed on how they perform in terms of yield and quality, particularly in different geographical regions of the US.
Lignin in Growing Alfalfa
Alfalfa forage yield is generally highest at full maturity. However forage quality decreases with plant maturity, due to an increase in lignin content. Generally, as the plant matures lignin content increases which will result in reduced digestibility. Differences in the digestibility of the alfalfa fiber fraction can result in a difference in animal performance when forages with a similar relative feed value (RFV) index are fed. The relative feed quality index (RFQ) has been developed to overcome this difference. This index takes into consideration the differences in digestibility of the fiber fraction and can be used to more accurately predict animal performance and match animal needs. Alfalfas with lower lignin content can be expected to have higher RFQs. Producers have attempted in the past, targeting specific harvest dates and maturities (late-bud to one tenth bloom) that result in the best compromise between forage quality and yield.
What are the advantages for reduced lignin in alfalfa?
(Example Hi-Gest Alfalfa)
Several publications have described that with this alfalfa producers would have at least four general harvest options:
- Produce dairy quality haylage or hay by taking advantage of reduction in lignin, and harvesting fields on a 28 day cutting schedule.
- Producers can extend the peak harvest date by up to 7 days to 35 days versus 28 days. This option utilizes the low lignin trait to increase forage yield without sacrificing quality.
- Flexibility at harvest time helps producers minimize the effect of bad weather and reduction in forage quality. Most of the synthetic varieties harvested at later dates would have lower forage quality and therefore higher lignin content.
- Producers can use low lignin traits for market flexibility.
Things to look forward
- Impact on milk production.
- Cost of the seed and values for forage quality with a week of delay in first cut.
- Better prices when alfalfas are marketed by relative feed value or relative feed quality.